US20230380238A1 - Color display with color filter layer comprising two-dimensional photonic crystals formed in a dielectric layer - Google Patents
Color display with color filter layer comprising two-dimensional photonic crystals formed in a dielectric layer Download PDFInfo
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/30—Devices specially adapted for multicolour light emission
- H10K59/38—Devices specially adapted for multicolour light emission comprising colour filters or colour changing media [CCM]
-
- H01L27/322—
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133509—Filters, e.g. light shielding masks
- G02F1/133514—Colour filters
-
- H01L27/3232—
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/50—OLEDs integrated with light modulating elements, e.g. with electrochromic elements, photochromic elements or liquid crystal elements
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F2202/00—Materials and properties
- G02F2202/32—Photonic crystals
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K50/00—Organic light-emitting devices
- H10K50/80—Constructional details
- H10K50/85—Arrangements for extracting light from the devices
- H10K50/852—Arrangements for extracting light from the devices comprising a resonant cavity structure, e.g. Bragg reflector pair
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K50/00—Organic light-emitting devices
- H10K50/80—Constructional details
- H10K50/85—Arrangements for extracting light from the devices
- H10K50/858—Arrangements for extracting light from the devices comprising refractive means, e.g. lenses
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/10—OLED displays
- H10K59/12—Active-matrix OLED [AMOLED] displays
- H10K59/1201—Manufacture or treatment
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
- H10K59/30—Devices specially adapted for multicolour light emission
- H10K59/35—Devices specially adapted for multicolour light emission comprising red-green-blue [RGB] subpixels
- H10K59/351—Devices specially adapted for multicolour light emission comprising red-green-blue [RGB] subpixels comprising more than three subpixels, e.g. red-green-blue-white [RGBW]
Definitions
- OLED organic light emitting diode
- QD quantum dot
- AMOLED active matrix OLED
- FIG. 1 diagrammatically illustrates a high level side-sectional view of a color display employing an electroluminescent material emitting white light and a color filter layer made up of photonic crystals comprising two-dimensional (2D) arrays of features formed in a dielectric layer.
- FIG. 2 diagrammatically illustrates operation of a color filter layer made up of photonic crystals comprising 2D arrays of features formed in a dielectric layer.
- FIG. 3 diagrammatically illustrates a top view of a photonic crystal comprising a 2D array of features formed in a dielectric layer.
- FIG. 4 diagrammatically illustrates an enlarged perspective view of a central portion of the photonic crystal of FIG. 3 .
- FIG. 5 diagrammatically illustrates the same enlarged perspective view of the central portion of the photonic crystal of FIG. 3 as is shown in FIG. 4 , but with an inner cavity and outer zone delineated.
- FIGS. 6 and 7 diagrammatically illustrate two layout embodiments for red, green, and blue photonic crystals forming a pixel of a color display.
- FIG. 8 diagrammatically illustrates an array of pixels as shown in FIG. 6 spanning a display area of a color display.
- FIGS. 9 , 10 , and 11 diagrammatically illustrate Section S-S indicated in FIG. 4 , according to three respective embodiments.
- FIG. 12 shows a flow chart of a suitable manufacturing method for forming a multicolor light emission structure of a color display employing an electroluminescent material emitting white light and including a color filter layer made up of photonic crystals comprising 2D arrays of features formed in a dielectric layer.
- FIG. 13 diagrammatically illustrates a high level side-sectional view of a color display employing red-emitting, green-emitting, and blue-emitting electroluminescent materials and a color filter layer made up of photonic crystals comprising 2D arrays of features formed in a dielectric layer.
- first and second features are formed in direct contact
- additional features may be formed between the first and second features, such that the first and second features may not be in direct contact
- present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
- spatially relative terms such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures.
- the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.
- the apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.
- the following relates to color displays of types employing an electroluminescent material optically coupled with an array of color filters of at least three different colors.
- the three different filter colors are suitably primary colors, typically red, green, and blue for a light-emissive color display.
- Embodiments disclosed herein employ a color filter layer made up of photonic crystals comprising two-dimensional (2D) arrays of features formed in a dielectric layer.
- the disclosed color displays employing color filters in accordance with this approach provide numerous advantages such as low cost manufacturing with a small number of workflow steps or operations, improved planarity of the multicolor light emission structure of a color display, facility for high precision and run-to-run reproducibility in defining the emission wavelengths, and facilitation of scalability to smaller pixel size (and hence higher resolution display), in some embodiments entailing only employing a different photomask to achieve a multicolor light emission structure with a different (e.g. higher) pixel resolution.
- a high level side-sectional view is diagrammatically illustrated of a color display employing a multicolor emission structure that includes an electroluminescent material 10 designed to emit white light, and a color filter layer 12 made up of photonic crystals 20 R, 20 G, 20 B comprising 2D arrays of features formed in a dielectric layer.
- the photonic crystals are tuned to red, green, and blue primary colors, i.e. the photonic crystals 20 R are tuned to red, the photonic crystals 20 G are tuned to green, and the photonic crystals 20 B are tuned to blue.
- electrodes 22 , 24 are arranged to electrically energize the electroluminescent material 10 to output light.
- FIG. 1 a high level side-sectional view is diagrammatically illustrated of a color display employing a multicolor emission structure that includes an electroluminescent material 10 designed to emit white light, and a color filter layer 12 made up of photonic crystals 20 R, 20 G, 20 B comprising 2D arrays of features formed in a dielectric layer.
- the electroluminescent material 10 outputs white light including at least all three primary (e.g. red, green, and blue) color components. (More typically, the output white light has a spectrum extending over most or all of the visible range, i.e. 400-700 nm wavelength).
- the electroluminescent material is an organic electroluminescent diode (OLED) material. In some embodiments, the electroluminescent material is a colloidal quantum dot (QD) electroluminescent material. Other types of electroluminescent materials are also contemplated as thew electroluminescent material 10 . In the illustrative examples, the electroluminescent material 10 is an OLED material, and the electrodes 22 , 24 include a cathode 22 and an anode 24 . It is to be understood that FIG. 1 is a high-level diagrammatic representation, and the multicolor emission structure 10 , 12 and associated electrodes 22 , 24 may include numerous additional layers or components not shown.
- additional layers or components may for example include an electron injection or transport layer (EIL or ETL) disposed between the cathode 22 and the emission structure 10 , 12 , and/or a hole transport or injection layer (HTL or HIL) disposed between the anode 24 and the emission structure 10 , 12 .
- EIL or ETL electron injection or transport layer
- HTL or HIL hole transport or injection layer
- the ordering of the stack of layers shown in FIG. 1 could be varied—for example, it is contemplated for one of the electrodes 22 , 24 to be interposed between the electroluminescent material 10 and the color filter layer 12 .
- the overall structure may be disposed on (and optionally formed on) a substrate made of glass, sapphire, or another material, and various additional layers may be provided as interface modification layers or the like.
- These additional components may be configured to structure the color display as a bottom-emitting display in which the display is observed from the substrate-side (in which case the light passes through the substrate which should be transparent over the spectrum of interest, e.g. over the visible spectrum), or as a top-emitting display in which the display is observed from the side opposite the substrate.
- the bottom-emitting configuration is sometimes referred to as a bottom-emitting OLED display (BEOLED) and the top-emitting configuration is sometimes referred to as a top-emitting OLED display (TEOLED).
- the configuration for bottom- or top-emission includes making the electrode on the emission side optically transparent over the visible spectrum (for example, made of indium tin oxide, i.e. ITO or a sufficiently thin metal to be light-transmissive) and making the electrode on the side opposite the emission side optically reflective over the visible spectrum (for example, made of gold or another metal of sufficient thickness to be optically opaque).
- the electrode on the emission side optically transparent over the visible spectrum for example, made of indium tin oxide, i.e. ITO or a sufficiently thin metal to be light-transmissive
- the electrode on the side opposite the emission side optically reflective over the visible spectrum for example, made of gold or another metal of sufficient thickness to be optically opaque.
- the color display typically includes control circuitry 30 configured to selectively apply an electrical bias 32 (e.g., voltage or current) to selected pixels of the display, or to sub-pixels of particular color(s) of the selected pixels, to form a desired color image.
- the control circuitry 30 is diagrammatically shown in FIG. 1 separately from the optical stack, but in some implementations is constructed as an electronics layer incorporated into the optical stack (i.e., the stack including the electroluminescent material 10 and the color filter layer 12 , along with the electrodes 22 , 24 ).
- the control circuitry 30 may implement an active matrix addressing scheme.
- such active matrix control circuitry may comprise a thin-film transistor (TFT) array in which the TFTs are, for example, polycrystalline silicon (poly-Si) or amorphous silicon (a-Si) TFTs, together with at least one of the electrodes 22 , 24 being segmented to form addressable pixels each of which is independently electrically biased (or not biased, depending on the content being displayed) by a corresponding TFT of the array of TFTs.
- the color display may be referred to as an active-matrix OLED display (AMOLED display).
- the control circuitry 30 may implement a passive matrix addressing scheme.
- the control circuitry 30 typically forms a backplane (e.g., a TFT backplane) that is disposed on the side of the light emission structure (e.g. comprising the electroluminescent material 10 and layer of photonic crystals 20 R, 20 G, 20 B) opposite from the light-emission side.
- the TFT backplane is fabricated on a glass, sapphire or other substrate, and the optical stack 10 , 12 and electrodes 22 , 24 are then fabricated on the TFT backplane, although other fabrication sequences are contemplated such as separately fabricating the TFT backplane and the optical stack and subsequently bonding the two stacks together.
- the color filter layer 12 is made up of photonic crystals 20 R, 20 G, 20 B where each photonic crystal comprises a two-dimensional (2D) array 40 of features 42 formed in a dielectric layer 44 , as diagrammatically shown in FIG. 2 .
- the dielectric layer 44 has a first refractive index, denoted herein as n 1 , which may vary as a function of wavelength due to dispersion but is usually relatively constant over the visible spectrum of about 400-700 nm.
- n 1 first refractive index
- SiO 2 varies from about 1.47 at 400 nm to about 1.45 at 700 nm.
- the dielectric layer is typically an oxide layer such as a silicon oxide layer, for example stoichiometric SiO 2 or a silicon oxide of another stoichiometry. More generally, the dielectric layer 44 can be any dielectric material which is suitably translucent or transparent over the visible spectrum, such as silicon nitride (e.g. stoichiometric Si 3 N 4 ), hafnium oxide (e.g. stoichiometric HfO 2 ), or so forth.
- the features 42 of each 2D array 40 of features 42 may, for example, comprise air or a filler dielectric material (that is different from the dielectric material of the dielectric layer 44 ).
- the features 42 may comprise the electroluminescent material 10 , which can be convenient from a manufacturing standpoint as the features comprising electroluminescent material 10 can be formed by filling openings etched into the dielectric layer 44 with the electroluminescent material 10 in a single spin coating or other deposition step that also deposits the electroluminescent material 10 as a layer on the color filter layer 12 as shown in FIG. 1 .
- the features 42 of each 2D array 40 have a second refractive index, denoted herein as n 2 , which is different from the first refractive index n 1 of the dielectric layer 44 . Put another way, n 1 ⁇ n 2 .
- the second refractive index may vary as a function of wavelength due to dispersion but is usually relatively constant over the visible spectrum of about 400-700 nm. For example, the refractive index of air is about 1.00 over the visible spectrum.
- FIGS. 3 , 4 , and 5 an illustrative example of a generic photonic crystal 20 comprising a 2D array 40 of features 42 formed in a dielectric layer 44 is shown.
- the illustrative 2D array 40 of FIG. 3 is a hexagonal array 40 of features 42 ; however, the array could have other geometries (for example, rectangular arrays as shown for the photonic crystals 20 R, 20 G, and 20 B of FIG. 2 ).
- the features 42 of each 2D array 40 of features 42 forming a photonic crystal are periodically spaced, so that the photonic crystal is tuned to a resonant wavelength by a periodicity of the 2D array 40 of features 42 .
- the 2D periodicity of the array 40 of features 42 is two-dimensional in that the features 42 have inter-feature spacing that is periodic in two non-parallel in-plane directions, such as in x- and y-directions. This is shown in the enlarged view of FIG. 4 , as a spacing L x along an x-direction and a spacing L y along a y-direction that is orthogonal to the x-direction in the plane of the dielectric layer 44 .
- the periodicities may be written as:
- n pc is the refractive index of the photonic crystal (which is typically about equal to the first refractive index n 1 of the dielectric material, neglecting the effect of the second refractive index n 2 of the features of the array of features on the photonic crystal medium)
- m x and m y are odd positive integers.
- n pc that is, its value as a function of wavelength
- the value of n pc for that wavelength is suitably used.
- the value n pc ( ⁇ res,R ) is suitably used when selecting the periodicities L x and L y for the red photonic crystal 20 R (where ⁇ res,R is the resonant wavelength of red light), and analogously for the green and blue photonic crystals 20 G and 20 B.
- m x m y , however this may not be the case in some other embodiments.
- the periodicity of the 2D array 40 of features 42 beneficially provides for the photonic crystal (for example, generic photonic crystal 20 of FIG. 3 ) to be tuned to the target resonant wavelength Ares by the periodicity of the 2D array 40 of features 42 .
- this periodicity is removed in a central region of the 2D array 40 of features 42 , thus forming a cavity within which the light (e.g. light 52 R, 52 G, or 52 B of FIG. 2 ) is strongly confined.
- FIG. 5 illustrates the same enlarged perspective view of the central portion of the photonic crystal of FIG. 3 that is shown in FIG. 4 , but with labeling of the dielectric layer 44 and the features 42 .
- a central cavity 46 is delineated by a boundary 47
- a peripheral zone or region 48 is delineated as the portion of the photonic crystal 20 lying outside of the boundary 47 .
- the features 42 are omitted, thus forming a cavity of the photonic crystal 20 within which the light (e.g. light 52 R, 52 G, or 52 B of FIG.
- the light output by the electroluminescent material 10 is enhanced significantly by resonant coupling within the central cavity 46 , thus substantially increasing the intensity of the light at the resonant wavelength ⁇ res of the photonic crystal 20 and providing the desired spectral filtering to ⁇ res .
- the boundary 47 is hexagonal, however depending on the photonic crystal design this boundary could have a circular, square, or other geometry.
- the central cavity 46 may in some embodiments includes relatively few of the features 42 , optionally with a central-most portion containing none of the features as shown, and the features 42 that are in the central cavity 46 may be staggered as shown.
- the outer zone or region 48 contains the features 42 with the specified periodicity, e.g. as designed using Equations (1) and (2). It is to be appreciated that this is merely an illustrative example.
- each photonic crystal 20 R, 20 G, and 20 B (or, more generically, for the photonic crystal 20 of FIGS. 3 - 5 ) comprises a corresponding 2D array 40 of features 42 formed in the dielectric layer 44 , which is tuned to the target resonant wavelength ⁇ res (e.g., ⁇ res is a red wavelength for a red photonic crystal 20 R, ⁇ res is a green wavelength for a green photonic crystal 20 G, and ⁇ res is a blue wavelength for a blue photonic crystal 20 B) by the periodicity L x and L y of the two-dimensional array 40 of features 42 making up that photonic crystal.
- ⁇ res is a red wavelength for a red photonic crystal 20 R
- ⁇ res is a green wavelength for a green photonic crystal 20 G
- ⁇ res is a blue wavelength for a blue photonic crystal 20 B
- Equations (1) and (2) can be used to design the periodicity for a given resonant wavelength ⁇ res and the refractive index n pc of the photonic crystal (and more particularly n pc at the specific target ⁇ res if the refractive index dispersion is sufficient to call for using a wavelength-specific refractive index).
- the electrodes 22 , 24 electrically energize the electroluminescent material 10 to emit white light 50 (see FIG. 2 ) that is optically coupled with a photonic crystal, the white light 50 is laterally confined in the plane of the dielectric layer 44 by the 2D array 40 of features 42 —that is, the 2D array 40 of features 42 forms a photonic crystal.
- confined resonant light in the plane of the dielectric layer 44 within the photonic crystals is diagrammatically depicted by arrows.
- the red photonic crystal 20 R is resonant for red light 52 R.
- the green photonic crystal 20 G is resonant for green light 52 G.
- the blue photonic crystal 20 B is resonant for blue light 52 B.
- the wavelength ⁇ res of the light which is resonant for each photonic crystal depends on the periodicity of the features 42 of the array 40 of features 42 making up that photonic crystal.
- the strength of the optical resonance provided by the photonic crystal depends in part on the difference between the first refractive index n 1 of the host dielectric layer 44 and the second refractive index n 2 of the features 42 .
- This difference can be quantified, for example, using the refractive index contrast ⁇ given by:
- a larger value for the refractive index contrast ⁇ generally leads to stronger resonance and improved color selection by the photonic crystal.
- the photonic crystal can suitably operate with either n 1 >n 2 or with n 1 ⁇ n 2 .
- the first-color photonic crystals e.g. red photonic crystals 20 R
- the second-color photonic crystals e.g. green photonic crystals 20 G
- the third-color photonic crystals e.g. blue photonic crystals 20 B
- the pixel 60 of FIG. 6 has photonic crystals formed by hexagonal arrays 40 of features 42 (such as that shown in FIG. 3 ), while the pixel 62 of FIG.
- FIG. 7 has photonic crystals formed by rectangular arrays 40 of features 42 (such as that shown in FIG. 2 ). These are merely illustrative examples. Moreover, while the illustrative pixels 60 and 62 have one red photonic crystal 20 R, one green photonic crystal 20 G, and one blue photonic crystal 20 B, it is contemplated to include more than one of selected crystals—for example, some display designs may have each pixel include two green photonic crystals 20 G to improve the perceived color balance.
- each pixel 60 or 62 further include a white element 64 to provide a higher quality of white light than might be achieved by operating the red, green, and blue “sub-pixels” together.
- the white element 64 if included, can be readily implemented by not including any array of features in the area of the dielectric layer 44 corresponding to the white element 64 . In this way, the white light 50 is not modified by any photonic crystal in that area and hence is output as high quality white light.
- the TFT array backplane 30 in an active matrix design suitably include an additional TFT for controlling emission of the white light 50 at the location of the white element 64 ).
- the pixel could incorporate an additional color element, i.e. a fourth-color photonic crystal tuned to a fourth resonant wavelength different from the first, second, and third resonant wavelengths, or even a fifth-color photonic crystal or more.
- an additional color element i.e. a fourth-color photonic crystal tuned to a fourth resonant wavelength different from the first, second, and third resonant wavelengths, or even a fifth-color photonic crystal or more.
- the first-color photonic crystals 20 R, the second-color photonic crystals 20 G, and the third-color photonic crystals 20 B are arranged to form an array of pixels 60 or 62 spanning a display area 66 of the color display.
- Illustrative example of FIG. 8 shows by way of nonlimiting illustrative example pixels 60 of FIG. 6 (without the optional white element 64 ) spanning the display area 66 ; however, the pixels could be otherwise designed, such as the rectangular pixels 62 of FIG. 7 , and/or the pixels can include the white element 64 .
- FIG. 8 shows by way of nonlimiting illustrative example pixels 60 of FIG. 6 (without the optional white element 64 ) spanning the display area 66 ; however, the pixels could be otherwise designed, such as the rectangular pixels 62 of FIG. 7 , and/or the pixels can include the white element 64 .
- a typical computer display may have a 1920 ⁇ 1080 array of pixels 60 , as one specific non-limiting illustrative example.
- FIGS. 9 - 11 depict Section S-S indicated in FIG. 4 and corresponding to a plane oriented perpendicular to the plane of the dielectric layer 44 (and hence also perpendicular to the plane of the color filter layer 12 ) and that passes through three features 42 , according to three different embodiments.
- the features 42 are cylindrical features 42 comprising cylindrical openings 70 passing through the dielectric layer 44 , with a central axis 72 of each opening oriented perpendicular to the plane 74 of the dielectric layer 44 .
- the cylindrical openings 70 can have any cross-sectional shape, e.g. circular, oval, square, rectangular, hexagonal, or so forth.
- the cylindrical openings 70 can, for example, be formed by photolithographically controlled etching of the dielectric layer 44 .
- the electroluminescent material 10 disposed as a coating on the color filter layer 12 .
- the features 42 comprise the cylindrical openings 70 filled with air.
- the electroluminescent material 10 is sufficiently viscous and the cross-sectional diameter of the cylindrical openings 70 is small enough so that the electroluminescent material 10 does not flow into the openings 70 .
- the features 42 comprise filler dielectric material 80 forming cylindrical features 42 passing through the dielectric layer 44 .
- the cylindrical filler dielectric material features 42 of this embodiment have cylinder axes 72 again oriented perpendicular to the plane 74 of the dielectric layer.
- These cylindrical filler dielectric material features 42 may be formed by photolithographically controlled etching of the dielectric layer 44 to form cylindrical openings analogous to the cylindrical openings 70 of the embodiment of FIG. 9 , followed by a deposition process in which the openings are filled with the filler dielectric material 80 .
- this entails a spin coating, sputtering, or other suitable deposition of the filler dielectric material 80 followed by chemical-mechanical polishing (CMP) to remove any filler dielectric material coating the surface of the dielectric layer 44 .
- CMP chemical-mechanical polishing
- An advantage of this embodiment is that the second refractive index n 2 is the refractive index of the filler dielectric material 80 , and hence the second refractive index n 2 is amenable to design by choice of the filler dielectric material 80 .
- the filler dielectric material 80 could be a high-k dielectric material such as silicon nitride (Si 3 N 4 , yielding n 2 ⁇ 2.0-2.1 depending on wavelength).
- the features 42 comprise portions of the electroluminescent material 10 filling openings that pass through the dielectric layer 44 (analogous to the openings 70 of the embodiment of FIG. 9 ).
- the features 42 comprising cylindrical portions of the translucent material 10 of this embodiment have cylinder axes 72 yet again oriented perpendicular to the plane 74 of the dielectric layer.
- These cylindrical portions of the translucent material forming the features 42 may be formed by photolithographically controlled etching of the dielectric layer 44 to form cylindrical openings analogous to the cylindrical openings 70 of the embodiment of FIG.
- the electroluminescent material 10 is sufficiently fluid and the cross-sectional diameter of the cylindrical openings is large enough so that the electroluminescent material 10 flows into the openings.
- the second refractive index n 2 is the refractive index of the electroluminescent material 10 .
- Another advantage of this embodiment is that the portions of the electroluminescent material 10 disposed in the openings passing through the dielectric layer 44 can be energized by the electrodes 22 , 24 (see FIG. 1 ) so as to increase to total volume of the electroluminescent material 10 providing the light 50 (see FIG. 2 ).
- a flow chart is shown of a manufacturing method for forming a multicolor light emission structure of a color display employing an electroluminescent material emitting white light and including a color filter layer made up of photonic crystals comprising 2D arrays of features formed in a dielectric layer.
- the manufacturing method of FIG. 12 could be used to manufacture the light emission structure of FIG. 1 including the electroluminescent layer 10 and the color filter layer 12 as previously described.
- the method starts with forming a dielectric layer (for example, the dielectric layer 44 ). This may be done, for example, by depositing silicon dioxide (SiO 2 ) or another chosen dielectric material on a suitable substrate such as a glass or sapphire substrate or the like. In some embodiments the substrate may have a previously formed TFT backplate or other electronics layer constituting the control circuitry 30 diagrammatically shown in FIG. 1 .
- the operation 100 deposits the dielectric layer 44 with uniform thickness.
- the resulting color filter layer 12 will also be of uniform thickness. This provides a planar surface on which subsequent layers of the color display are deposited, which can simplify manufacturing and improve reliability and/or performance of the manufactured color display.
- a two-dimensional array of openings is formed in the dielectric layer. These openings may constitute the features 42 of the 2D array 40 of features 42 as in the embodiment of FIG. 9 .
- an optional operation 104 after forming the openings they may be filled with filler dielectric material, e.g. with filler dielectric material 80 forming cylindrical features 42 passing through the dielectric layer 44 as in the embodiment of FIG. 10 .
- electroluminescent material is formed on the dielectric layer.
- the electroluminescent material formed in the operation 106 may be the electroluminescent material 10 as previously described.
- the operation 106 may deposit the electroluminescent material 10 on the dielectric layer using spin coating or another suitable approach.
- the material deposited by spin coating or the like to form the electroluminescent material 10 as an OLED material comprises a liquid polymer containing fluorescent or phosphorescent dye, polymer, or other suitable molecule.
- the material deposited by spin coating or the like to form the electroluminescent material 10 comprises a liquid polymer containing colloidal quantum dots (QDs) so as to form the electroluminescent material as a colloidal QD electroluminescent material.
- the operation 106 may form the electroluminescent material as a multilayer stack, for example including electron and/or hole injection or transport layer(s).
- the operation 106 also results in the electroluminescent material filling the openings made in operation 102 , as indicated by block 108 of FIG. 12 , so as to form the features 42 of the 2D array 40 of features 42 as cylindrical columns of the electroluminescent material 10 passing through the dielectric layer.
- an advantage of the above-described manufacturing process is that it can be performed in some embodiments using only a single photolithography mask 110 for the operation 102 to form all of the 2D arrays 40 of features 42 of all photonic crystals of the color filter layer 12 .
- the color filter layer is constructed using, for example, dielectric layers of different thicknesses for the different resonant wavelengths (e.g. red, green, and blue), then multiple photomasks will typically be used to form the regions with these different thicknesses.
- the approach of FIG. 12 is readily scalable to form multicolor light emission structures for color displays of different display resolutions, by employing an embodiment of the photomask 110 for the desired display resolution.
- the wavelength selection provided by the photonic crystals is determined by the periodicity of the 2D arrays of features which is in turn determined by the photomask 110 , this results in the manufacturing process of FIG. 12 providing precise run-to-run reproducibility in defining the emission wavelengths.
- the embodiments described thus far employ the white electroluminescent material 10 which outputs white light when energized by the electrodes 22 , 24 .
- the red, green, and blue (or other primary colors) of the color display are achieved by wavelength selection provided by the photonic crystals 20 R, 20 G, and 20 B.
- FIG. 13 another color display embodiment is similar to that of FIG. 1 , except that in the embodiment of FIG. 13 the white electroluminescent material 10 is replaced by regions of red electroluminescent material 10 R, regions of green electroluminescent material 10 G, and regions of blue electroluminescent material 10 B (or, more generally, by regions of first-color electroluminescent material 10 R, regions of second-color electroluminescent material 10 G, and regions of third-color electroluminescent material 10 B). As shown in FIG.
- the regions of red electroluminescent material 10 R are aligned with corresponding red photonic crystals 20 R
- the regions of green electroluminescent material 10 G are aligned with corresponding green photonic crystals 20 G
- the regions of blue electroluminescent material 10 B are aligned with corresponding blue photonic crystals 20 B.
- Operation of this embodiment is analogous to that of FIG. 1 , except that in this case the photonic crystals serve to improve the color purity of the red, green, and blue light output by the respective red, green, and blue electroluminescent material 10 R, 10 G, and 10 B.
- a color display comprises: a color filter layer comprising an array of photonic crystals formed in a dielectric layer having a first refractive index; an electroluminescent material optically coupled with the color filter layer; and electrodes arranged to electrically energize the electroluminescent material to output light.
- Each photonic crystal includes a 2D array of features. The features have a second refractive index different from the first refractive index. The photonic crystal is tuned to a resonant wavelength by a periodicity of the 2D array of features.
- the array of photonic crystals includes first-color photonic crystals tuned to a first resonant wavelength, second-color photonic crystals tuned to a second resonant wavelength that is different from the first resonant wavelength, and third-color photonic crystals tuned to a third resonant wavelength that is different from the first resonant wavelength and that is different from the second resonant wavelength.
- the first-color photonic crystals, the second-color photonic crystals, and the third-color photonic crystals are arranged to form an array of pixels spanning a display area of the color display, in which each pixel includes at least one first-color photonic crystal, at least one second-color photonic crystal, and at least one third-color photonic crystal.
- a method of fabricating a color display comprises forming a dielectric layer over a display area of the color display wherein the dielectric layer has a first refractive index, forming 2D arrays of features in the dielectric layer, and coating the dielectric layer with an electroluminescent material.
- the 2D arrays of features formed in the dielectric layer include: first 2D arrays of features having a first periodicity and forming first-color photonic crystals tuned to a first resonant wavelength; second 2D arrays of openings having a second periodicity that is different from the first periodicity and forming second-color photonic crystals tuned to a second resonant wavelength different from the first resonant wavelength; and third 2D arrays of openings having a third periodicity that is different from the first periodicity and that is different from the second periodicity and forming third-color photonic crystals tuned to a third resonant wavelength different from the first resonant wavelength and different from the second resonant wavelength.
- a color display comprises a color filter layer including a dielectric layer with a first refractive index and with an array of photonic crystals formed therein, an electroluminescent material disposed on the color filter layer, and electrodes arranged to electrically energize the electroluminescent material to cause the electroluminescent material to output white light.
- Each photonic crystal includes a 2D array of features. The features have a second refractive index different from the first refractive index.
- the 2D array of features includes a central cavity within which the features of the 2D array of features are omitted.
- Each photonic crystal is tuned to a resonant wavelength by a periodicity of the two-dimensional array of features.
- the array of photonic crystals include red photonic crystals tuned to a red resonant wavelength, green photonic crystals tuned to a green resonant wavelength, and blue photonic crystals tuned to a blue resonant wavelength.
- the red photonic crystals, the green photonic crystals, and the blue photonic crystals are arranged to form an array of pixels spanning a display area of the color display, in which each pixel includes at least one red photonic crystal, at least one green photonic crystal, and at least one blue photonic crystal.
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Abstract
In a color display, a color filter layer includes a dielectric layer with an array of photonic crystals, an electroluminescent material disposed on the color filter layer, and electrodes arranged to electrically energize the electroluminescent material to output white light. Each photonic crystal includes a two-dimensional (2D) array of features. The 2D array of features includes a central cavity within which the features of the 2D array of features are omitted. Each photonic crystal is tuned to a resonant wavelength by a periodicity of the two-dimensional array of features. The array of photonic crystals may include, for example, red, green, and blue photonic crystals arranged to form an array of pixels spanning a display area of the color display, in which each pixel includes at least one red photonic crystal, at least one green photonic crystal, and at least one blue photonic crystal.
Description
- The following relates to the color display arts, organic light emitting diode (OLED) display arts, quantum dot (QD) display device arts, active matrix OLED (AMOLED) display arts, and related arts.
- Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
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FIG. 1 diagrammatically illustrates a high level side-sectional view of a color display employing an electroluminescent material emitting white light and a color filter layer made up of photonic crystals comprising two-dimensional (2D) arrays of features formed in a dielectric layer. -
FIG. 2 diagrammatically illustrates operation of a color filter layer made up of photonic crystals comprising 2D arrays of features formed in a dielectric layer. -
FIG. 3 diagrammatically illustrates a top view of a photonic crystal comprising a 2D array of features formed in a dielectric layer. -
FIG. 4 diagrammatically illustrates an enlarged perspective view of a central portion of the photonic crystal ofFIG. 3 . -
FIG. 5 diagrammatically illustrates the same enlarged perspective view of the central portion of the photonic crystal ofFIG. 3 as is shown inFIG. 4 , but with an inner cavity and outer zone delineated. -
FIGS. 6 and 7 diagrammatically illustrate two layout embodiments for red, green, and blue photonic crystals forming a pixel of a color display. -
FIG. 8 diagrammatically illustrates an array of pixels as shown inFIG. 6 spanning a display area of a color display. -
FIGS. 9, 10, and 11 diagrammatically illustrate Section S-S indicated inFIG. 4 , according to three respective embodiments. -
FIG. 12 shows a flow chart of a suitable manufacturing method for forming a multicolor light emission structure of a color display employing an electroluminescent material emitting white light and including a color filter layer made up of photonic crystals comprising 2D arrays of features formed in a dielectric layer. -
FIG. 13 diagrammatically illustrates a high level side-sectional view of a color display employing red-emitting, green-emitting, and blue-emitting electroluminescent materials and a color filter layer made up of photonic crystals comprising 2D arrays of features formed in a dielectric layer. - The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
- Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.
- The following relates to color displays of types employing an electroluminescent material optically coupled with an array of color filters of at least three different colors. For a full-color display, the three different filter colors are suitably primary colors, typically red, green, and blue for a light-emissive color display. Embodiments disclosed herein employ a color filter layer made up of photonic crystals comprising two-dimensional (2D) arrays of features formed in a dielectric layer. The disclosed color displays employing color filters in accordance with this approach provide numerous advantages such as low cost manufacturing with a small number of workflow steps or operations, improved planarity of the multicolor light emission structure of a color display, facility for high precision and run-to-run reproducibility in defining the emission wavelengths, and facilitation of scalability to smaller pixel size (and hence higher resolution display), in some embodiments entailing only employing a different photomask to achieve a multicolor light emission structure with a different (e.g. higher) pixel resolution.
- With reference to
FIG. 1 , a high level side-sectional view is diagrammatically illustrated of a color display employing a multicolor emission structure that includes anelectroluminescent material 10 designed to emit white light, and acolor filter layer 12 made up ofphotonic crystals photonic crystals 20R are tuned to red, thephotonic crystals 20G are tuned to green, and thephotonic crystals 20B are tuned to blue. Furthermore,electrodes electroluminescent material 10 to output light. In the example ofFIG. 1 , theelectroluminescent material 10 outputs white light including at least all three primary (e.g. red, green, and blue) color components. (More typically, the output white light has a spectrum extending over most or all of the visible range, i.e. 400-700 nm wavelength). - In some embodiments, the electroluminescent material is an organic electroluminescent diode (OLED) material. In some embodiments, the electroluminescent material is a colloidal quantum dot (QD) electroluminescent material. Other types of electroluminescent materials are also contemplated as thew
electroluminescent material 10. In the illustrative examples, theelectroluminescent material 10 is an OLED material, and theelectrodes cathode 22 and ananode 24. It is to be understood thatFIG. 1 is a high-level diagrammatic representation, and themulticolor emission structure electrodes electroluminescent material 10 is an OLED material, such additional layers or components may for example include an electron injection or transport layer (EIL or ETL) disposed between thecathode 22 and theemission structure anode 24 and theemission structure FIG. 1 could be varied—for example, it is contemplated for one of theelectrodes electroluminescent material 10 and thecolor filter layer 12. The overall structure may be disposed on (and optionally formed on) a substrate made of glass, sapphire, or another material, and various additional layers may be provided as interface modification layers or the like. - These additional components may be configured to structure the color display as a bottom-emitting display in which the display is observed from the substrate-side (in which case the light passes through the substrate which should be transparent over the spectrum of interest, e.g. over the visible spectrum), or as a top-emitting display in which the display is observed from the side opposite the substrate. For the OLED display example, the bottom-emitting configuration is sometimes referred to as a bottom-emitting OLED display (BEOLED) and the top-emitting configuration is sometimes referred to as a top-emitting OLED display (TEOLED). In general, the configuration for bottom- or top-emission includes making the electrode on the emission side optically transparent over the visible spectrum (for example, made of indium tin oxide, i.e. ITO or a sufficiently thin metal to be light-transmissive) and making the electrode on the side opposite the emission side optically reflective over the visible spectrum (for example, made of gold or another metal of sufficient thickness to be optically opaque).
- Furthermore, the color display typically includes
control circuitry 30 configured to selectively apply an electrical bias 32 (e.g., voltage or current) to selected pixels of the display, or to sub-pixels of particular color(s) of the selected pixels, to form a desired color image. Thecontrol circuitry 30 is diagrammatically shown inFIG. 1 separately from the optical stack, but in some implementations is constructed as an electronics layer incorporated into the optical stack (i.e., the stack including theelectroluminescent material 10 and thecolor filter layer 12, along with theelectrodes 22, 24). By way of some nonlimiting illustrative examples, thecontrol circuitry 30 may implement an active matrix addressing scheme. For example, such active matrix control circuitry may comprise a thin-film transistor (TFT) array in which the TFTs are, for example, polycrystalline silicon (poly-Si) or amorphous silicon (a-Si) TFTs, together with at least one of theelectrodes electroluminescent material 10, the color display may be referred to as an active-matrix OLED display (AMOLED display). In other embodiments, thecontrol circuitry 30 may implement a passive matrix addressing scheme. Thecontrol circuitry 30 typically forms a backplane (e.g., a TFT backplane) that is disposed on the side of the light emission structure (e.g. comprising theelectroluminescent material 10 and layer ofphotonic crystals optical stack electrodes - With continuing reference to
FIG. 1 and with further reference toFIG. 2 , in some illustrative embodiments thecolor filter layer 12 is made up ofphotonic crystals array 40 offeatures 42 formed in adielectric layer 44, as diagrammatically shown inFIG. 2 . Thedielectric layer 44 has a first refractive index, denoted herein as n1, which may vary as a function of wavelength due to dispersion but is usually relatively constant over the visible spectrum of about 400-700 nm. For example, the refractive index of SiO2 varies from about 1.47 at 400 nm to about 1.45 at 700 nm. The dielectric layer is typically an oxide layer such as a silicon oxide layer, for example stoichiometric SiO2 or a silicon oxide of another stoichiometry. More generally, thedielectric layer 44 can be any dielectric material which is suitably translucent or transparent over the visible spectrum, such as silicon nitride (e.g. stoichiometric Si3N4), hafnium oxide (e.g. stoichiometric HfO2), or so forth. Thefeatures 42 of each2D array 40 offeatures 42 may, for example, comprise air or a filler dielectric material (that is different from the dielectric material of the dielectric layer 44). In another embodiments, thefeatures 42 may comprise theelectroluminescent material 10, which can be convenient from a manufacturing standpoint as the features comprisingelectroluminescent material 10 can be formed by filling openings etched into thedielectric layer 44 with theelectroluminescent material 10 in a single spin coating or other deposition step that also deposits theelectroluminescent material 10 as a layer on thecolor filter layer 12 as shown inFIG. 1 . Thefeatures 42 of each2D array 40 have a second refractive index, denoted herein as n2, which is different from the first refractive index n1 of thedielectric layer 44. Put another way, n1≠n2. Again, the second refractive index may vary as a function of wavelength due to dispersion but is usually relatively constant over the visible spectrum of about 400-700 nm. For example, the refractive index of air is about 1.00 over the visible spectrum. - With reference to
FIGS. 3, 4, and 5 , an illustrative example of ageneric photonic crystal 20 comprising a2D array 40 offeatures 42 formed in adielectric layer 44 is shown. Theillustrative 2D array 40 ofFIG. 3 is ahexagonal array 40 offeatures 42; however, the array could have other geometries (for example, rectangular arrays as shown for thephotonic crystals FIG. 2 ). Thefeatures 42 of each2D array 40 offeatures 42 forming a photonic crystal are periodically spaced, so that the photonic crystal is tuned to a resonant wavelength by a periodicity of the2D array 40 offeatures 42. The 2D periodicity of thearray 40 offeatures 42 is two-dimensional in that thefeatures 42 have inter-feature spacing that is periodic in two non-parallel in-plane directions, such as in x- and y-directions. This is shown in the enlarged view ofFIG. 4 , as a spacing Lx along an x-direction and a spacing Ly along a y-direction that is orthogonal to the x-direction in the plane of thedielectric layer 44. In some embodiments, the periodicities may be written as: -
- where λres is the resonant wavelength in a vacuum (which is equivalent to the resonant wavelength in air since the refractive index nair of air is suitably close to the ideal refractive index n=1 for a vacuum), npc is the refractive index of the photonic crystal (which is typically about equal to the first refractive index n1 of the dielectric material, neglecting the effect of the second refractive index n2 of the features of the array of features on the photonic crystal medium), and mx and my are odd positive integers. If the dispersion of npc (that is, its value as a function of wavelength) cannot be neglected, then in designing a photonic crystal for each of the red, green, and blue (or each of other primary colors) the value of npc for that wavelength is suitably used. In other words, the value npc(λres,R) is suitably used when selecting the periodicities Lx and Ly for the
red photonic crystal 20R (where λres,R is the resonant wavelength of red light), and analogously for the green and bluephotonic crystals - As previously discussed with reference to Equations (1) and (2), the periodicity of the
2D array 40 offeatures 42 beneficially provides for the photonic crystal (for example,generic photonic crystal 20 ofFIG. 3 ) to be tuned to the target resonant wavelength Ares by the periodicity of the2D array 40 offeatures 42. However, in the illustrative embodiments, this periodicity is removed in a central region of the2D array 40 offeatures 42, thus forming a cavity within which the light (e.g. light 52R, 52G, or 52B ofFIG. 2 ) is strongly confined. - With reference to
FIG. 5 , this is illustrated for thehexagonal photonic crystal 20 ofFIG. 3 .FIG. 5 illustrates the same enlarged perspective view of the central portion of the photonic crystal ofFIG. 3 that is shown inFIG. 4 , but with labeling of thedielectric layer 44 and thefeatures 42. As labeled inFIG. 5 , acentral cavity 46 is delineated by aboundary 47, and a peripheral zone orregion 48 is delineated as the portion of thephotonic crystal 20 lying outside of theboundary 47. In the core of thecentral cavity 46, thefeatures 42 are omitted, thus forming a cavity of thephotonic crystal 20 within which the light (e.g. light 52R, 52G, or 52B ofFIG. 2 ) is strongly confined by thefeatures 42. The light output by theelectroluminescent material 10 is enhanced significantly by resonant coupling within thecentral cavity 46, thus substantially increasing the intensity of the light at the resonant wavelength λres of thephotonic crystal 20 and providing the desired spectral filtering to λres. - In the illustrative embodiment, the
boundary 47 is hexagonal, however depending on the photonic crystal design this boundary could have a circular, square, or other geometry. Thecentral cavity 46 may in some embodiments includes relatively few of thefeatures 42, optionally with a central-most portion containing none of the features as shown, and thefeatures 42 that are in thecentral cavity 46 may be staggered as shown. The outer zone orregion 48 contains thefeatures 42 with the specified periodicity, e.g. as designed using Equations (1) and (2). It is to be appreciated that this is merely an illustrative example. - With returning reference to
FIGS. 1 and 2 , eachphotonic crystal photonic crystal 20 ofFIGS. 3-5 ) comprises acorresponding 2D array 40 offeatures 42 formed in thedielectric layer 44, which is tuned to the target resonant wavelength λres (e.g., λres is a red wavelength for ared photonic crystal 20R, λres is a green wavelength for agreen photonic crystal 20G, and λres is a blue wavelength for a bluephotonic crystal 20B) by the periodicity Lx and Ly of the two-dimensional array 40 offeatures 42 making up that photonic crystal. Equations (1) and (2) can be used to design the periodicity for a given resonant wavelength λres and the refractive index npc of the photonic crystal (and more particularly npc at the specific target λres if the refractive index dispersion is sufficient to call for using a wavelength-specific refractive index). When theelectrodes electroluminescent material 10 to emit white light 50 (seeFIG. 2 ) that is optically coupled with a photonic crystal, thewhite light 50 is laterally confined in the plane of thedielectric layer 44 by the2D array 40 offeatures 42—that is, the2D array 40 offeatures 42 forms a photonic crystal. There is no analogous confinement in the direction transverse to the plane of thedielectric layer 44 since there is no periodicity in that direction. (Some limited optical confinement could be present due to any abrupt refractive index step at the surfaces of thedielectric layer 44; however, if this is a problem then anti-reflection coatings could be added to these surfaces to further reduce or eliminate optical confinement transverse to the plane of the dielectric layer 44). - With continuing reference to
FIG. 2 , confined resonant light in the plane of thedielectric layer 44 within the photonic crystals is diagrammatically depicted by arrows. Particularly, thered photonic crystal 20R is resonant forred light 52R. Thegreen photonic crystal 20G is resonant forgreen light 52G. The bluephotonic crystal 20B is resonant forblue light 52B. As already described with reference to Equations (1) and (2), the wavelength λres of the light which is resonant for each photonic crystal depends on the periodicity of thefeatures 42 of thearray 40 offeatures 42 making up that photonic crystal. The strength of the optical resonance provided by the photonic crystal depends in part on the difference between the first refractive index n1 of thehost dielectric layer 44 and the second refractive index n2 of thefeatures 42. This difference can be quantified, for example, using the refractive index contrast Δ given by: -
- A larger value for the refractive index contrast Δ generally leads to stronger resonance and improved color selection by the photonic crystal. The photonic crystal can suitably operate with either n1>n2 or with n1<n2.
- With reference to
FIGS. 6 and 7 , moreover, the first-color photonic crystals (e.g. redphotonic crystals 20R), the second-color photonic crystals (e.g.green photonic crystals 20G), and the third-color photonic crystals (e.g. bluephotonic crystals 20B) are suitably arranged to form a pixel 60 (FIG. 6 ) or pixel 62 (FIG. 7 ) that includes at least one first-color photonic crystal 20R, at least one second-color photonic crystal 20G, and at least one third-color photonic crystal 20B. Thepixel 60 ofFIG. 6 has photonic crystals formed byhexagonal arrays 40 of features 42 (such as that shown inFIG. 3 ), while thepixel 62 ofFIG. 7 has photonic crystals formed byrectangular arrays 40 of features 42 (such as that shown inFIG. 2 ). These are merely illustrative examples. Moreover, while theillustrative pixels red photonic crystal 20R, onegreen photonic crystal 20G, and oneblue photonic crystal 20B, it is contemplated to include more than one of selected crystals—for example, some display designs may have each pixel include twogreen photonic crystals 20G to improve the perceived color balance. - Furthermore, as indicated by dashed lines in
FIGS. 6 and 7 , it is contemplated to have eachpixel white element 64 to provide a higher quality of white light than might be achieved by operating the red, green, and blue “sub-pixels” together. Thewhite element 64, if included, can be readily implemented by not including any array of features in the area of thedielectric layer 44 corresponding to thewhite element 64. In this way, thewhite light 50 is not modified by any photonic crystal in that area and hence is output as high quality white light. (In such a design, theTFT array backplane 30 in an active matrix design suitably include an additional TFT for controlling emission of thewhite light 50 at the location of the white element 64). As another contemplated variant, instead of adding thewhite element 64 the pixel could incorporate an additional color element, i.e. a fourth-color photonic crystal tuned to a fourth resonant wavelength different from the first, second, and third resonant wavelengths, or even a fifth-color photonic crystal or more. - With reference to
FIG. 8 , it will be further understood that to implement the color display the first-color photonic crystals 20R, the second-color photonic crystals 20G, and the third-color photonic crystals 20B are arranged to form an array ofpixels display area 66 of the color display. Illustrative example ofFIG. 8 shows by way of nonlimitingillustrative example pixels 60 ofFIG. 6 (without the optional white element 64) spanning thedisplay area 66; however, the pixels could be otherwise designed, such as therectangular pixels 62 ofFIG. 7 , and/or the pixels can include thewhite element 64.FIG. 8 is diagrammatic, and it will be appreciated that in typical color displays for televisions, color computer displays, or the like the number ofpixels 60 is much larger than shown, e.g. a typical computer display may have a 1920×1080 array ofpixels 60, as one specific non-limiting illustrative example. - With reference back to
FIGS. 3-5 and with further reference toFIGS. 9, 10, and 11 , some suitable approaches for fabricating thecolor filter layer 12 including thefeatures 42 are described.FIGS. 9-11 depict Section S-S indicated inFIG. 4 and corresponding to a plane oriented perpendicular to the plane of the dielectric layer 44 (and hence also perpendicular to the plane of the color filter layer 12) and that passes through threefeatures 42, according to three different embodiments. - With particular reference to
FIG. 9 , in this embodiment thefeatures 42 arecylindrical features 42 comprisingcylindrical openings 70 passing through thedielectric layer 44, with acentral axis 72 of each opening oriented perpendicular to theplane 74 of thedielectric layer 44. Thecylindrical openings 70 can have any cross-sectional shape, e.g. circular, oval, square, rectangular, hexagonal, or so forth. Thecylindrical openings 70 can, for example, be formed by photolithographically controlled etching of thedielectric layer 44. Also shown inFIG. 9 is theelectroluminescent material 10 disposed as a coating on thecolor filter layer 12. In the embodiment ofFIG. 9 , thefeatures 42 comprise thecylindrical openings 70 filled with air. This can be achieved if, for example, theelectroluminescent material 10 is sufficiently viscous and the cross-sectional diameter of thecylindrical openings 70 is small enough so that theelectroluminescent material 10 does not flow into theopenings 70. In another approach, the air-filledopenings 70 can be formed after deposition of theelectroluminescent material 10. Because theopenings 70 are filled with air, in this embodiment the second refractive index for thefeatures 42 is the refractive index of air, that is, n2=1.00. - With particular reference to
FIG. 10 , in this embodiment thefeatures 42 comprisefiller dielectric material 80 formingcylindrical features 42 passing through thedielectric layer 44. The cylindrical filler dielectric material features 42 of this embodiment havecylinder axes 72 again oriented perpendicular to theplane 74 of the dielectric layer. These cylindrical filler dielectric material features 42 may be formed by photolithographically controlled etching of thedielectric layer 44 to form cylindrical openings analogous to thecylindrical openings 70 of the embodiment ofFIG. 9 , followed by a deposition process in which the openings are filled with thefiller dielectric material 80. In one suitable approach, this entails a spin coating, sputtering, or other suitable deposition of thefiller dielectric material 80 followed by chemical-mechanical polishing (CMP) to remove any filler dielectric material coating the surface of thedielectric layer 44. An advantage of this embodiment is that the second refractive index n2 is the refractive index of thefiller dielectric material 80, and hence the second refractive index n2 is amenable to design by choice of thefiller dielectric material 80. For example, if thedielectric layer 44 is a low-k dielectric material such as silicon dioxide (SiO2, for which n1=1.47 at 400 nm to about n1=1.45 at 700 nm) then thefiller dielectric material 80 could be a high-k dielectric material such as silicon nitride (Si3N4, yielding n2≅2.0-2.1 depending on wavelength). - With particular reference to
FIG. 11 , in this embodiment thefeatures 42 comprise portions of theelectroluminescent material 10 filling openings that pass through the dielectric layer 44 (analogous to theopenings 70 of the embodiment ofFIG. 9 ). Thefeatures 42 comprising cylindrical portions of thetranslucent material 10 of this embodiment havecylinder axes 72 yet again oriented perpendicular to theplane 74 of the dielectric layer. These cylindrical portions of the translucent material forming thefeatures 42 may be formed by photolithographically controlled etching of thedielectric layer 44 to form cylindrical openings analogous to thecylindrical openings 70 of the embodiment ofFIG. 9 , followed by deposition of theelectroluminescent material 10 over the surface of thedielectric layer 44 such a way that the depositedelectroluminescent material 10 also flows into and fills those cylindrical openings. To achieve such filling, theelectroluminescent material 10 is sufficiently fluid and the cross-sectional diameter of the cylindrical openings is large enough so that theelectroluminescent material 10 flows into the openings. In this embodiment, the second refractive index n2 is the refractive index of theelectroluminescent material 10. An advantage of this embodiment is that no additional step is performed to fill the openings (versus the embodiment ofFIG. 10 which entails the additional deposition/CMP to deposit thefiller dielectric material 80 in the openings). Another advantage of this embodiment is that the portions of theelectroluminescent material 10 disposed in the openings passing through thedielectric layer 44 can be energized by theelectrodes 22, 24 (seeFIG. 1 ) so as to increase to total volume of theelectroluminescent material 10 providing the light 50 (seeFIG. 2 ). - With reference to
FIG. 12 , a flow chart is shown of a manufacturing method for forming a multicolor light emission structure of a color display employing an electroluminescent material emitting white light and including a color filter layer made up of photonic crystals comprising 2D arrays of features formed in a dielectric layer. For example the manufacturing method ofFIG. 12 could be used to manufacture the light emission structure ofFIG. 1 including theelectroluminescent layer 10 and thecolor filter layer 12 as previously described. The method starts with forming a dielectric layer (for example, the dielectric layer 44). This may be done, for example, by depositing silicon dioxide (SiO2) or another chosen dielectric material on a suitable substrate such as a glass or sapphire substrate or the like. In some embodiments the substrate may have a previously formed TFT backplate or other electronics layer constituting thecontrol circuitry 30 diagrammatically shown inFIG. 1 . - In some embodiments, the
operation 100 deposits thedielectric layer 44 with uniform thickness. As a consequence, the resultingcolor filter layer 12 will also be of uniform thickness. This provides a planar surface on which subsequent layers of the color display are deposited, which can simplify manufacturing and improve reliability and/or performance of the manufactured color display. - In an
operation 102, a two-dimensional array of openings is formed in the dielectric layer. These openings may constitute thefeatures 42 of the2D array 40 offeatures 42 as in the embodiment ofFIG. 9 . Alternatively, in anoptional operation 104, after forming the openings they may be filled with filler dielectric material, e.g. withfiller dielectric material 80 formingcylindrical features 42 passing through thedielectric layer 44 as in the embodiment ofFIG. 10 . - In an
operation 106, electroluminescent material is formed on the dielectric layer. For example, the electroluminescent material formed in theoperation 106 may be theelectroluminescent material 10 as previously described. Theoperation 106 may deposit theelectroluminescent material 10 on the dielectric layer using spin coating or another suitable approach. In a nonlimiting illustrative embodiment, the material deposited by spin coating or the like to form theelectroluminescent material 10 as an OLED material comprises a liquid polymer containing fluorescent or phosphorescent dye, polymer, or other suitable molecule. In another nonlimiting illustrative embodiment, the material deposited by spin coating or the like to form theelectroluminescent material 10 comprises a liquid polymer containing colloidal quantum dots (QDs) so as to form the electroluminescent material as a colloidal QD electroluminescent material. Optionally, theoperation 106 may form the electroluminescent material as a multilayer stack, for example including electron and/or hole injection or transport layer(s). For embodiments in accordance withFIG. 11 , theoperation 106 also results in the electroluminescent material filling the openings made inoperation 102, as indicated byblock 108 ofFIG. 12 , so as to form thefeatures 42 of the2D array 40 offeatures 42 as cylindrical columns of theelectroluminescent material 10 passing through the dielectric layer. - With continuing reference to
FIG. 12 , an advantage of the above-described manufacturing process is that it can be performed in some embodiments using only asingle photolithography mask 110 for theoperation 102 to form all of the2D arrays 40 offeatures 42 of all photonic crystals of thecolor filter layer 12. By contrast, if the color filter layer is constructed using, for example, dielectric layers of different thicknesses for the different resonant wavelengths (e.g. red, green, and blue), then multiple photomasks will typically be used to form the regions with these different thicknesses. Moreover, the approach ofFIG. 12 is readily scalable to form multicolor light emission structures for color displays of different display resolutions, by employing an embodiment of thephotomask 110 for the desired display resolution. Still further, as the wavelength selection provided by the photonic crystals is determined by the periodicity of the 2D arrays of features which is in turn determined by thephotomask 110, this results in the manufacturing process ofFIG. 12 providing precise run-to-run reproducibility in defining the emission wavelengths. - With returning reference to
FIG. 1 , the embodiments described thus far employ thewhite electroluminescent material 10 which outputs white light when energized by theelectrodes photonic crystals - With reference to
FIG. 13 , another color display embodiment is similar to that ofFIG. 1 , except that in the embodiment ofFIG. 13 thewhite electroluminescent material 10 is replaced by regions ofred electroluminescent material 10R, regions of green electroluminescent material 10G, and regions of blueelectroluminescent material 10B (or, more generally, by regions of first-color electroluminescent material 10R, regions of second-color electroluminescent material 10G, and regions of third-color electroluminescent material 10B). As shown inFIG. 13 , the regions ofred electroluminescent material 10R are aligned with corresponding redphotonic crystals 20R, the regions of green electroluminescent material 10G are aligned with correspondinggreen photonic crystals 20G, and the regions of blueelectroluminescent material 10B are aligned with corresponding bluephotonic crystals 20B. Operation of this embodiment is analogous to that ofFIG. 1 , except that in this case the photonic crystals serve to improve the color purity of the red, green, and blue light output by the respective red, green, and blueelectroluminescent material - In the following, some further embodiments are described.
- In a nonlimiting illustrative embodiment, a color display comprises: a color filter layer comprising an array of photonic crystals formed in a dielectric layer having a first refractive index; an electroluminescent material optically coupled with the color filter layer; and electrodes arranged to electrically energize the electroluminescent material to output light. Each photonic crystal includes a 2D array of features. The features have a second refractive index different from the first refractive index. The photonic crystal is tuned to a resonant wavelength by a periodicity of the 2D array of features. The array of photonic crystals includes first-color photonic crystals tuned to a first resonant wavelength, second-color photonic crystals tuned to a second resonant wavelength that is different from the first resonant wavelength, and third-color photonic crystals tuned to a third resonant wavelength that is different from the first resonant wavelength and that is different from the second resonant wavelength. The first-color photonic crystals, the second-color photonic crystals, and the third-color photonic crystals are arranged to form an array of pixels spanning a display area of the color display, in which each pixel includes at least one first-color photonic crystal, at least one second-color photonic crystal, and at least one third-color photonic crystal.
- In a nonlimiting illustrative embodiment, a method of fabricating a color display comprises forming a dielectric layer over a display area of the color display wherein the dielectric layer has a first refractive index, forming 2D arrays of features in the dielectric layer, and coating the dielectric layer with an electroluminescent material. The 2D arrays of features formed in the dielectric layer include: first 2D arrays of features having a first periodicity and forming first-color photonic crystals tuned to a first resonant wavelength; second 2D arrays of openings having a second periodicity that is different from the first periodicity and forming second-color photonic crystals tuned to a second resonant wavelength different from the first resonant wavelength; and third 2D arrays of openings having a third periodicity that is different from the first periodicity and that is different from the second periodicity and forming third-color photonic crystals tuned to a third resonant wavelength different from the first resonant wavelength and different from the second resonant wavelength.
- In a nonlimiting illustrative embodiment, a color display comprises a color filter layer including a dielectric layer with a first refractive index and with an array of photonic crystals formed therein, an electroluminescent material disposed on the color filter layer, and electrodes arranged to electrically energize the electroluminescent material to cause the electroluminescent material to output white light. Each photonic crystal includes a 2D array of features. The features have a second refractive index different from the first refractive index. The 2D array of features includes a central cavity within which the features of the 2D array of features are omitted. Each photonic crystal is tuned to a resonant wavelength by a periodicity of the two-dimensional array of features. The array of photonic crystals include red photonic crystals tuned to a red resonant wavelength, green photonic crystals tuned to a green resonant wavelength, and blue photonic crystals tuned to a blue resonant wavelength. The red photonic crystals, the green photonic crystals, and the blue photonic crystals are arranged to form an array of pixels spanning a display area of the color display, in which each pixel includes at least one red photonic crystal, at least one green photonic crystal, and at least one blue photonic crystal.
- The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.
Claims (20)
1. A color display comprising:
a color filter layer comprising an array of photonic crystals formed in a dielectric layer having a first refractive index;
an electroluminescent material optically coupled with the color filter layer; and
electrodes arranged to electrically energize the electroluminescent material to output light;
wherein each photonic crystal includes a two-dimensional array of features, the features having a second refractive index different from the first refractive index, the photonic crystal being tuned to a resonant wavelength by a periodicity of the two-dimensional array of features;
wherein the array of photonic crystals includes first-color photonic crystals tuned to a first resonant wavelength, second-color photonic crystals tuned to a second resonant wavelength that is different from the first resonant wavelength, and third-color photonic crystals tuned to a third resonant wavelength that is different from the first resonant wavelength and that is different from the second resonant wavelength; and
wherein the first-color photonic crystals, the second-color photonic crystals, and the third-color photonic crystals are arranged to form an array of pixels spanning a display area of the color display, in which each pixel includes at least one first-color photonic crystal, at least one second-color photonic crystal, and at least one third-color photonic crystal.
2. The color display of claim 1 wherein the dielectric layer has a uniform thickness across the display area of the color display.
3. The color display of claim 1 wherein the electroluminescent material comprises a coating disposed on the dielectric layer.
4. The color display of claim 3 wherein:
the electroluminescent material also fills openings in the dielectric layer of the color filter layer,
the features of the two-dimensional array of features comprise the openings in the dielectric layer filled with the electroluminescent material, and
the electroluminescent material has the second refractive index.
5. The color display of claim 1 wherein the features of the two-dimensional array of features comprise openings in the dielectric layer filled with air or filler dielectric material, and wherein the second refractive index is the refractive index of the air or filler dielectric material.
6. The color display of claim 1 wherein the features of the two-dimensional array of features comprise cylindrical features that pass through the dielectric layer and have cylinder axes oriented perpendicular to a plane of the dielectric layer.
7. The color display of claim 1 wherein the periodicity of the two-dimensional array of features includes a first periodicity with a period Lx along a first direction x in a plane of the dielectric layer and a second periodicity with a period Ly along a second direction y in the plane of the dielectric layer.
8. The color display of claim 1 wherein each photonic crystal further includes a central cavity within which the features of the two-dimensional array of features are omitted.
9. The color display of claim 1 wherein the electroluminescent material comprises an organic electroluminescent diode (OLED) material or a colloidal quantum dot (QD) electroluminescent material.
10. The color display of claim 1 wherein the electroluminescent material emits white light when electrically energized by the electrodes.
11. The color display of claim 1 wherein the electroluminescent material includes:
first-color electroluminescent material emitting light of a first color that includes the first resonant wavelength, the first-color electroluminescent material being optically coupled with the first-color photonic crystals tuned to the first resonant wavelength;
second-color electroluminescent material emitting light of a second color that includes the second resonant wavelength, the second-color electroluminescent material being optically coupled with the second-color photonic crystals tuned to the second resonant wavelength; and
third-color electroluminescent material emitting light of a third color that includes the third resonant wavelength, the third-color electroluminescent material being optically coupled with the third-color photonic crystals tuned to the third resonant wavelength.
12. The color display of claim 1 wherein the first resonant wavelength is a red wavelength, the second resonant wavelength is a green wavelength, and the third resonant wavelength is a blue wavelength.
13. A method of fabricating a color display, the method comprising:
forming a dielectric layer over a display area of the color display wherein the dielectric layer has a first refractive index;
forming two-dimensional arrays of features in the dielectric layer; and
coating the dielectric layer with an electroluminescent material;
wherein the two-dimensional arrays of features formed in the dielectric layer include:
first two-dimensional arrays of features having a first periodicity and forming first-color photonic crystals tuned to a first resonant wavelength,
second two-dimensional arrays of openings having a second periodicity that is different from the first periodicity and forming second-color photonic crystals tuned to a second resonant wavelength different from the first resonant wavelength, and
third two-dimensional arrays of openings having a third periodicity that is different from the first periodicity and that is different from the second periodicity and forming third-color photonic crystals tuned to a third resonant wavelength different from the first resonant wavelength and different from the second resonant wavelength.
14. The method of claim 13 wherein the forming of the dielectric layer comprises forming the dielectric layer with a uniform thickness over the display area.
15. The method of claim 13 wherein the electroluminescent material has a second refractive index which is different from the first refractive index, and the forming of the two-dimensional arrays of features in the dielectric layer includes:
before the coating of the dielectric layer with the electroluminescent material, forming two-dimensional arrays of openings in the dielectric layer;
wherein the coating of the dielectric layer with the electroluminescent material further fills the openings of the two-dimensional arrays of openings with the electroluminescent material, the features of the two-dimensional arrays of features being the openings in the dielectric layer filled with the electroluminescent material.
16. The method of claim 13 wherein the forming of the two-dimensional arrays of features in the dielectric layer includes:
forming two-dimensional arrays of openings in the dielectric layer; and
filling the openings in the dielectric layer with a filler dielectric material having a second refractive index that is different from the first refractive index.
17. The method of claim 13 wherein the forming of the two-dimensional arrays of features in the dielectric layer includes:
forming two-dimensional arrays of openings in the dielectric layer by photolithographically controlled etching using a single photolithography mask, the features of the two-dimensional arrays of features being the openings or the openings filled by a filler material or the openings filled by the electroluminescent material.
18. The method of claim 13 wherein the electroluminescent material comprises an organic electroluminescent diode (OLED) material or a colloidal quantum dot (QD) electroluminescent material.
19. A color display comprising:
a color filter layer comprising a dielectric layer with a first refractive index and with an array of photonic crystals formed therein;
an electroluminescent material disposed on the color filter layer; and
electrodes arranged to electrically energize the electroluminescent material to cause the electroluminescent material to output white light;
wherein each photonic crystal includes a two-dimensional array of features, the features having a second refractive index different from the first refractive index, the two-dimensional array of features including a central cavity within which the features of the two-dimensional array of features are omitted, the photonic crystal being tuned to a resonant wavelength by a periodicity of the two-dimensional array of features; and
wherein the array of photonic crystals include red photonic crystals tuned to a red resonant wavelength, green photonic crystals tuned to a green resonant wavelength, and blue photonic crystals tuned to a blue resonant wavelength; and
wherein the red photonic crystals, the green photonic crystals, and the blue photonic crystals are arranged to form an array of pixels spanning a display area of the color display, in which each pixel includes at least one red photonic crystal, at least one green photonic crystal, and at least one blue photonic crystal.
20. The color display of claim 19 wherein the features comprise cylindrical columns of the electroluminescent material passing through the dielectric layer, wherein the electroluminescent material has the second refractive index.
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US17/749,295 US11832496B1 (en) | 2022-05-20 | 2022-05-20 | Color display with color filter layer comprising two-dimensional photonic crystals formed in a dielectric layer |
TW111149003A TW202346995A (en) | 2022-05-20 | 2022-12-20 | Color display with color filter layer comprising two-dimensional photonic crystals formed in a dielectric layer and method for forming the same |
US18/231,897 US20230389387A1 (en) | 2022-05-20 | 2023-08-09 | Color display with color filter layer comprising two-dimensional photonic crystals formed in a dielectric layer |
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050140286A1 (en) * | 2003-11-25 | 2005-06-30 | Hironori Ito | Luminescence cell, luminescence device with luminescence cell, luminescence unit, luminescence device with luminescence unit, frame for luminescence device, and method for manufacturing luminescence cell |
US20180190929A1 (en) * | 2015-07-01 | 2018-07-05 | Red Bank Technologies, LLC | Active matrix enhanced organic light emitting diode displays for large screen graphic display application |
US10529290B1 (en) * | 2018-02-27 | 2020-01-07 | Facebook Technologies, Llc | Non-uniformly patterned photonic crystal structures with quantum dots for pixelated color conversion |
US20200033671A1 (en) * | 2018-07-24 | 2020-01-30 | Beijing Boe Display Technology Co., Ltd. | Color filter substrate, manufacturing method thereof, and display device |
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US7292614B2 (en) | 2003-09-23 | 2007-11-06 | Eastman Kodak Company | Organic laser and liquid crystal display |
US20220085335A1 (en) | 2019-02-08 | 2022-03-17 | Sony Group Corporation | Light emitting element and display device |
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US20050140286A1 (en) * | 2003-11-25 | 2005-06-30 | Hironori Ito | Luminescence cell, luminescence device with luminescence cell, luminescence unit, luminescence device with luminescence unit, frame for luminescence device, and method for manufacturing luminescence cell |
US20180190929A1 (en) * | 2015-07-01 | 2018-07-05 | Red Bank Technologies, LLC | Active matrix enhanced organic light emitting diode displays for large screen graphic display application |
US10529290B1 (en) * | 2018-02-27 | 2020-01-07 | Facebook Technologies, Llc | Non-uniformly patterned photonic crystal structures with quantum dots for pixelated color conversion |
US20200033671A1 (en) * | 2018-07-24 | 2020-01-30 | Beijing Boe Display Technology Co., Ltd. | Color filter substrate, manufacturing method thereof, and display device |
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